Flexo is the best suitable and versatile method for printing on a wide range of materials for a variety of applications, such as rolled or flat-rigid and soft/deformable/flexible substrates, corrugated cardboard, foils, plastics film, aluminum foils, label materials, newsprint and more.
Modern flexography is a process that uses polymeric relief plates. The plate is coated by a film image mask, which is prepared separately and then attached to the virgin plate. The negative mask areas absorb and block UV light, while the transparent, positive, image-areas on the plate are exposed to the UV light through the mask and cured thereby. The plate then goes through a development process where the negative masked unexposed areas are etched away, leaving only the impression/cured printing ink holder-surface that later carries the printing ink and transfers it directly to the printed substrate material during the printing process.
The traditional method of preparing a flexo plate master through a film mask is a complex process which includes a plurality of steps, a variety of devices and is time consuming. The main step in such methods involves the direct application of a liquid formulation directly onto the flexographic plate. These available liquid coating techniques suffer, among others, from the following deficiencies:
1. The liquid coating methods employ a liquid solvent, which is most often volatile and toxic and may cause environmental contamination. Additionally, only a limited number of solvents may be used in the primer formulation, as improper selection of solvent can damage the flexographic plate surface;
2. The solubility of the coating materials in the desired solvent might be limited, thereby limiting choice of solvents;
3. The liquid coating methods require high temperatures for drying the coated film on top of the flexographic plate, causing photopolymer deformation and polymerization. When employed at a low temperature, a homogenous and uniform film coating is not typically obtained;
4. In the liquid coating methods for coating a single photopolymeric plate (vis-à-vis continuous coating technology), coating uniformity, homogeneity, stability and other surface mechanical characteristics are very difficult to control and maintain, especially at the plate edges; and
5. The liquid coating methods are cost ineffective.
Therefore, there is a demand to replace the available wet-coating processes for coating flexographic plates with shorter make-ready time (on demand), economically/simple, more environmentally friendly and more efficient process, which would overcome the aforementioned deficiencies associated with wet processes, maintain or increase the quality characteristics of traditional flexo printing processes and which will permit industrial and continuous material-efficient process.